Fibers made of polyethylene terephthalate or a polyester comprising polyethylene terephthalate as a main component has excellent heat resistance, chemical resistance, a high melting point and a high modulus of elasticity, therefore are thus widely used in curtains, carpets, clothes, blankets, sheetings, table clothes, upholstery fabrics, wall coverings, artificial hair, interior materials for automobiles, outdoor reinforcing materials, and safety nets.
On the other hand, human hair, artificial hair (modacrylic fibers, polyvinyl chloride fibers), or the like has been conventionally used in hair products such as wigs, hair wigs, extensions, hair bands, and doll hair. However, it has now become difficult to provide human hair for hair products, and thus artificial hair has become more important. Modacrylic fibers have been often used as artificial hair materials due to their flame retardance, but have only insufficient heat resistance.
In recent years, there has been proposed artificial hair using, as a main component, a polyester typified by polyethylene terephthalate having excellent heat resistance. However, fibers made of a polyester typified by polyethylene terephthalate are flammable materials, and thus have insufficient flame resistance.
Conventionally, various attempts have been made to improve flame resistance of polyester fibers. Known examples of such attempts include a method comprising using a fiber made of a polyester obtained by copolymerizing a flame retardant monomer containing a phosphorus atom, and a method comprising adding a flame retardant to a polyester fiber.
As the former method comprising copolymerizing a flame retardant monomer, a method comprising copolymerizing a phosphorus compound with excellent heat stability having a phosphorus atom as a ring member (Japanese Patent Publication No. 55-41610), a method comprising copolymerizing carboxyphosphinic acid (Japanese Patent Publication No. 53-13479), a method comprising copolymerizing a polyester containing a polyallylate with a phosphorus compound (Japanese Patent Laid-open No. 11-124732), or the like has been proposed.
As artificial hair to which the above flame retardant technology is applied, a polyester fiber copolymerized with a phosphorus compound has been proposed (Japanese Patent Laid-open No. 03-27105, Japanese Patent Laid-open No. 05-339805, etc.), for example.
However, since artificial hair is demanded to be highly flame resistant, such a copolymer polyester fiber must have a high copolymerization amount when used for artificial hair. This results in a significant decrease in flame resistance of the polyester, and causes other problems in which it is difficult to perform melt spinning, or, when flame approaches, the artificial hair does not catch fire and is not burned, but molten and dripped. When the phosphorus flame retardant is added, stickiness is increased because it must be added in a large amount to exhibit flame retardance, and the resulting artificial hair made of a polyester fiber tends to have a heat history and, under high humidity conditions, be devitrified to affect the appearance of the fiber.
On the other hand, as the latter method comprising adding a flame retardant, a method comprising adding a halogenated cycloalkane compound as fine particles to a polyester fiber (Japanese Patent Publication No. 03-57990), a method comprising adding a bromine-containing alkylcyclohexane to a polyester fiber (Japanese Patent Publication No. 01-24913), or the like has been proposed. However, in the method comprising adding a flame retardant to a polyester fiber, in order to achieve sufficient flame retardance, the addition treatment temperature must be as high as 150° C. or more, the addition treatment time must be long, or a large amount of a flame retardant must be used, disadvantageously. This causes problems such as deteriorated fiber properties, reduced productivity, and an increased production cost.
As described above, artificial hair has not yet been provided which maintains fiber properties possessed by a conventional polyester fiber such as flame resistance, heat resistance, and strength and elongation and has excellent setting properties, devitrification resistance, and stickiness reduction.
Synthetic fibers conventionally used for hair include acrylonitrile fibers, vinyl chloride fibers, vinylidene chloride fibers, polyester fibers, nylon fibers, and polyolefin fibers. Conventionally, these fibers have been processed into products for artificial hair such as wigs, braids, and extension hair. However, these fibers do not have properties necessary for a fiber for artificial hair such as heat resistance, curling properties, and good feeling together. Thus, products with various properties satisfied cannot be produced from a single fiber, and products making use of properties of each fiber are produced and used. Fibers having a cross-section suitable to characteristics of each goods have also been studied and improved.
Examples of such fibers include a filament for wigs having a cocoon cross-section with a length L of a longest part, a diameter W of round parts on both ends, and a width C of a central constriction, each within a specific range (Japanese Utility Model Laid-open No. 48-13277); a synthetic fiber for artificial hair having a largest diameter (L) passing through the gravity in the fiber cross-section within a specific range (Japanese Patent Publication No. 53-6253); a filament for wigs and braids having a Y-shaped cross-section in which four unit filaments having an almost round shape or an elliptical shape are provided with one unit filament radially adjacent to the other three unit filaments at the same intervals, and the adjacent unit filaments have contact points having a width almost equal to the radius of the unit filaments (Japanese Utility Model Laid-open No. 63-78026); and a filament for wigs having a cross-section with at least two flat circles lapped, in which the ratio L/W of the major axis length L to the minor axis length W, the distance between the centers of two adjacent flat circles, the angle between the straight line linking the centers of two adjacent flat circles and the major axes of the flat circles, and the like are limited (Japanese Patent Laid-open No. 55-51802).
However, any of the above-described conventional fibers developed as fibers for artificial hair has a cross-section with a length and an angle extremely limited and with a unique shape, and cannot necessarily easily produced. In addition, such fibers do not necessarily have preferable texture when used for braids or extension hair, and tend to be felt hard because the fibers are intended to keep a hairstyle or make the resulting hair straight. Further, these fibers cannot be sufficiently easily handled manually. Ribbon-section fibers have conventionally widely used for piles, but have been assumed to be inappropriate for use as fibers for artificial hair such as wigs due to their disliked too much softness or the like.
On the other hand, in the method comprising adding a flame retardant to a polyester fiber, in order to achieve sufficient flame retardance, the addition treatment temperature must be as high as 150° C. or higher, the addition treatment time must be long, or a large amount of a flame retardant must be used, disadvantageously. This causes problems such as deteriorated fiber properties, decreased productivity, and an increased production cost.
In order to provide such synthetic fibers poorly flame retardant or not flame retardant with flexibility, smooth feeling, or the like, various silicone finishing agents have been provided. Examples of the finishing agents for providing the fibers with flexibility, crease resistance, elastic force, and compression recovery properties include dimethylpolysiloxane, methylhydrogenpolysiloxane, dimethylpolysiloxane having hydroxyl groups at both terminals, a vinyl group-containing organopolysiloxane, an epoxy group-containing organopolysiloxane, an amino group-containing organopolysiloxane, an ester group-containing organopolysiloxane, and a polyoxyalkylene-containing organopolysiloxane. A treating agent composed of a combination of alkoxysilanes and/or a polyacrylamide resin or a catalyst or the like has also been known.
For example, there is disclosed a method using a treating agent composed of an organopolysiloxane containing at least two epoxy groups in one molecule and an organopolysiloxane containing an amino group, or a treating agent composed of an organopolysiloxane having hydroxyl groups at both terminals, and an organopolysiloxane containing an amino group and an alkoxy group in one molecule and/or its partial hydrolysate and condensate (Japanese Patent Publication No. 53-36079).
Further, there are described a treating agent composed of an organopolysiloxane containing an epoxy group and an aminoalkyltrialkoxysilane (Japanese Patent Publication No. 53-197159 and Japanese Patent Publication No. 53-19716), and a diorganopolysiloxane having triorganosiloxy groups at both terminals, which contains two or more amino groups in one molecule (Japanese Patent Publication No. 53-98499). In addition, there is proposed a method using a treating agent composed of an aminopolysiloxane containing two or more amino groups in one molecule and an alkoxysilane containing one or more reactive groups such as amino groups or epoxy groups (Japanese Patent Publication No. 58-17310).
Further, there are disclosed a method using a treating agent composed of a diorganosiloxane containing at least two amino groups in one molecule and a diorganopolysiloxane containing at least two ester bonds in one molecule (Japanese Patent Laid-open No. 55-152864), and a method using a polysiloxane containing an amino group, a hydroxyl group-terminated polysiloxane, and an alkylalkoxysilane containing a reactive group (Japanese Patent Laid-open No. 58-214585). In addition, there are disclosed a method using a treating agent composed of an organopolysiloxane containing an epoxy group, an aminosilane compound, and a curing catalyst (Japanese Patent Laid-open No. 59-144683), and a method using an organopolysiloxane containing at least two epoxy groups in one molecule and a polyacrylamide resin (Japanese Patent Laid-open No. 60-94680).
However, fibers to which these silicone-containing fiber treating agents are attached exhibit improved smooth feeling, combing properties, and the like, but the silicone-containing fiber treating agents are flammable, and thus provide significantly reduce flame retardance of flame retardant synthetic fibers, disadvantageously.